Update Clang ToT iOS builder to use the 8.3 SDK

ios/build/bots/chromium.fyi/ClangToTiOS.json

Index: ios/build/bots/chromium.fyi/ClangToTiOS.json
diff --git a/ios/build/bots/chromium.fyi/ClangToTiOS.json b/ios/build/bots/chromium.fyi/ClangToTiOS.json
index 26663dfc0db72752f759802006c0d4dcd4f8344b..b5a9e2a304e61fb30863e6ffa3bcc525cbf63709 100644
--- a/ios/build/bots/chromium.fyi/ClangToTiOS.json
+++ b/ios/build/bots/chromium.fyi/ClangToTiOS.json
@@ -3,9 +3,9 @@
     "hans"
   ],
   "comments": [
-    "Clang tip-of-tree builder for iOS"
+    "Clang tip-of-tree builder for iOS."
   ],
-  "xcode version": "6.2",
+  "xcode version": "6.3",
   "GYP_DEFINES": {
     "chromium_ios_signing": "0",
     "clang_use_chrome_plugins": "0",
@@ -17,7 +17,7 @@
   },
   "compiler": "ninja",
   "configuration": "Release",
-  "sdk": "iphoneos8.2",
+  "sdk": "iphoneos8.3",

[smut, 2015/05/20 21:33:56]

FYI simulator would cycle faster. To use simulator, change configuration to
Debug and sdk to iphonesimulator8.3. Simulator would also allow tests to be run,
as device tests are not supported upstream.

[hans, 2015/05/20 21:36:14]

Let's get the bot running first, and then we can try this out later.

   "tests": [
   ]
 }